The electric incandescent lamps applied in headlights of vehicles and in projector systems have to be arranged with high accuracy in an optical system determined by a basic plane. For carrying out this operation the incandescent lamp is equipped with a base element and fixed thereby in an optical adjusting arrangement. The base element is then slided in the arrangement in order to ensure the required position of the incandescent body which should lie in the focus plane of the body of the headlight or projector system. This is generally made by applying a centering plate made in form of a disc which is joined with the base element after completing the adjusting operation. The connection is generally ensured by brazing or welding. The disadvantage of the brazing process is its long time and therefore care should be done for preventing the high thermal load of the incandescent lamp. The general way of development is to exclude brazing and to apply a welding process which results in shortening the time of operation for joining the base element and the centering plate.
In the known incandescent lamp arrangements the centering plate is relativelly thick, the base element is thinner than the centering plate which is equipped with a flange element connecting the centering plate and the base element. The flange is protruding from the surface of the centering plate at the base element. If the centering plate and the base element should be joined by point welding, the flange element of the thick centering plate is pressed to the thin base element which can suffer deformation under the influence of this pressure.
The German patent document DE-OS 26.05.433 discloses an electric incandescent lamp having a base element made with hooked flange elements on its opposite longitudinal sides. The flange elements are arranged with ends lying in a gap between the centering plate and the base element and in this position it is possible to join the centering plate by its flange element with the base element. This construction is advantageous for welding but linked with difficult problems when the optical adjusting operation should be carried out. The hooked flange elements protrude from the surface of the base element and they end behind the edge of the opening of the centering plate. In this way relatively big connecting surfaces are ensured and this fact limits the possibility of precise translating necessary when the incandescent body of the lamp should be adjusted.